Vacuum Problem? Pics + Audio... Pls Help!!

[MegaChrisGT]

Greetings! I've got a 2000 GT convertible that has been making an awful vacuum sound when you shutdown the engine. You can hear the "sucking" sound somewhat while the motor is running. Performance seems to be unaffected, the engine idles, accelerates, etc, just as it should.

I recently replaced the IAC valve hoping this would solve the problem, but to no avail. Here is a photo of where the microphone was when the sound below was recorded. Can anyone identify the sensor/solenoid circled in red?

Here is a recording of the sound with the engine running, and then when it is most pronounced, when the engine is shut off.

Has anyone experienced something similar to this? I've been having this problem for months and can't chase it down. I've checked all the hoses I can see and haven't found any leaks. Any advice/info would be greatly appreciated.

Thanks in advance!!!!

 

[babeabe19]

when u kill yur engine all it does is stop the fuel ans spark from contuing there jobs. but it doesnt stop the pistions from moving up and down. so wat u hear is engine blowing of its compresion through the intake. thats y stock pieces are made of rubber and have silencers so that its not noticable under stock conditions.

oh and it doesnt just happen to yur car either. my car does it, my friends 94 GSR does it, alot of cars with bolt on mods do it